This invention relates to a bearing cooling mechanism for a vehicular AC generator.
The interior of vehicular AC generators is put at a considerably elevated temperature because they are exposed to hot air resulting from associated internal combustion engines and further generate heat due to both electric resistances of electric coils involved and frictional resistances of associated bearings. With the interior of such generators put at the elevated temperature, the bearings are impeded from being smoothly rotated which will, in turn, result in their fusing together. Accordingly, in order to avoid such a situation, the bearings have been formed of a material high in heat resistance. Alternatively the vehicular AC generators might be provided at one end with suction ports for sucking cooling air and at the other end with the cooling fan so that the cooling fan is rotated to suck the air into the interior thereof through the suction ports by means of the action of the resulting suction force thereby to cool the interior of the generators.
However, high heat resistance materials are expensive and the use thereof has resulted in a lack of economy. Also the use of the cooling mechanism as described above has been disadvantageous in that the bearings cannot be sufficiently cooled. This is because cooling air sucked through the suction ports is warmed in a clearance formed between a rotor and a stator of the generator and because the bearings are disposed at their positions where they are not exposed to the cooling air.
Accordingly, it is an object of the present invention to provide a new and improved bearing cooling mechanism for a vehicular AC generator which mechanism is enabled to sufficiently cool the bearings by directly exposing the latter to cooling air.